A significant portion of the soil of the Rocknest dune is crystalline and is consistent with derivation from unweathered basalt. Minerals and their compositions are identified by X-ray diffraction (XRD) data from the CheMin instrument on MSL Curiosity. Basalt minerals in the soil include plagioclase, olivine, low- and high-calcium pyroxenes, magnetite, ilmenite, and quartz. The only minerals unlikely to have formed in an unaltered basalt are hematite and anhydrite. The mineral proportions and compositions of the Rocknest soil are nearly identical to those of the Adirondack-class basalts of Gusev Crater, Mars, inferred from their bulk composition as analyzed by the MER Spirit rover

Achilles, C. N.

Anderosn, R. C.

Bish, D. L.

Blake, D. F.

Bristow, T. F.

Chipera, S. J.

Crisp, J. A.

DesMarais, D. J.

Downs, R. T.

Farmer, J. A.

Ming, D. W.

Morookian, J. M.

Morris, R. V.

Morrison, S. M.

Rampe, E. B.

Sarrazin, P.

Schmidt, M.

Spanovich, N.

Stolper, E. M.

Treiman, A. H.

Vaniman, D. T.

Yen, A. S.

NASA Technical Reports Server

BASALTIC SOIL OF GALE CRATER: CRYSTALLINE COMPONENT COMPARED TO MARTIAN 
BASALTS & METEORITES. A.H. Treiman1, D.L. Bish2, D.W. Ming3, R.V. Morris3, M. Schmidt4, R.T. Downs5, 
E.M. Stolper6, D.F. Blake7, D.T. Vaniman8, C.N. Achilles3, S.J. Chipera9, T.F. Bristow7, J.A. Crisp10, J.A. Farmer11, 
J.M. Morookian10, S.M. Morrison5, E.B. Rampe3, P. Sarrazin12, A.S. Yen10, R.C. Anderson10, D.J. DesMarais7, & N. 
Spanovich10. 1Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston TX 77058 (treiman#lpi.usra.edu), 
2Indiana U., 3NASA JSC, 4Brock U., 5U. Arizona, 6Caltech, 7NASA ARC, 8Planetary Science Institute, 9Chesapeake 
Energy, 10JPL, 11Arizona State U., 12In-Xitu.  
 
A significant portion of the soil of the Rocknest 
dune is crystalline and is consistent with derivation 
from unweathered basalt. Minerals and their composi-
tions are identified by X-ray diffraction (XRD) data 
from the  CheMin instrument on MSL Curiosity. Ba-
salt minerals in the soil include plagioclase, olivine, 
low- and high-calcium pyroxenes, magnetite, ilmenite, 
and quartz.  The only minerals unlikely to have formed 
in an unaltered basalt are hematite and anhydrite. The 
mineral proportions and compositions of the Rocknest 
soil are nearly identical to those of the Adirondack-
class basalts of Gusev Crater, Mars, inferred from their 
bulk composition as analyzed by the MER Spirit rover.  
Sample & Methods: XRD data were obtained by 
the MSL CheMin instrument [a,a’] on soil of the 
Rocknest Dune, from scoop portions #3, #4, & #5 
(which was analyzed by SAM for volatiles) [b]. The 
raw soil was scooped and sieved in the MSL CHIMRA 
instrument, which delivered to CheMin ~0.02 gram of 
the <150 µm size fraction. Those portions were ana-
lyzed by CheMin over several successive nights, for 
total integrations of ~12 and ~16 hours respectively. 
The raw 2-dimensional data were filtered for only 
CoK diffractions, summed to yield 2-D XRD pat-
terns, integrated circumferentially to give typical 1-D 
XRD patterns, and then summed to a single combined 
pattern [b] (Fig. 1). The soil contains a significant pro-
portion of X-ray amorphous materials [c,d], which 
appear as a background under the sharp diffractions 
investigated here. Diffraction positions were calibrated 
against a quartz-beryl standard within CheMin.  
The 1-D XRD pattern was analyzed by Rietveld re-
finement (Bruker AXS Topas) to  retrieve the propor-
tions, unit-cell, and compositions of crystalline phases 
present [b].  
Results:  CheMin XRD patterns of the Rocknest 
soil imply that its crystalline component is relatively 
simple, and composed almost entirely of minerals 
characteristic of fresh basalts. Mineral proportions are 
shown in Table 1, based on Rietveld refinement of the 
summed XRD pattern [b]. The presence of plagioclase, 
olivine, and two pyroxenes is certain. The composi-
tions of the olivine and plagioclase are nearly uniquely 
defined by their unit-cell parameters – olivine at 
Fo58±3 (taken as the Mg# of the silicates) and feldspar 
at An50±3. Pyroxene compositions are not uniquely 
defined by their unit-cell parameters, and work is in 
progress. Among other detections, those of hematite 
(~1%), magnetite, quartz, and anhydrite (~1%) are 
nearly certain; those of ilmenite and sanidine (a high-
temperature potassium feldspar, i.e. K-spar) are likely 
but not certain.  
Many minerals, likely or possible in a basalt, were 
not detected at the percent mass level. Among possible 
igneous minerals, there are no detections of Ca-
amphibole, biotite, nepheline, and Ca-phosphates. 
Among possible alteration minerals [i], there are no 
detections of Fe-Mg amphibole, serpentines, talc, chlo-
rites, epidote, zoisite, scapolite, muscovite, illite, goe-
thite, carbonate minerals, sulfides, and clay mineralss. 
Among possible pedogenic products, there are no de-
tections of sulfates other than anhydrite, carbonate 
minerals, clay minerals, perchlorates, and halides.  
 implications:  
Mineral compositions derived from CheMin XRD 
data (unit-cell parameters) are consistent, in general, 
with compositions of minerals in martian meteorites, 
and those inferred from bulk compositions of martian 
basalts. Plagioclase in the soil is andesine (~An50), 
Table 1, as inferred for little-altered olivine basalts 
from Gusev crater (Table 1), and as in martian meteor-
ites, Table 2 [g]. No planetary basalts other than mar-
tian and terrestrial contain such sodic plagioclase [g].  
Olivine in the Rocknest soil is of intermediate 
composition (Fo = Mg# ~58), consistent with the 
Mg#s of little-altered olivine basalt from Gusev crater 
(Table 1), and similar to the Mg#s of martian meteorite 
basalts (Table 2). Actual average Mg# of olivines in 
the martian meteorite basalts may be slightly higher 
than predicted by Mg# alone (unpublished data), al-
though the differences are small.  
Mineral proportions in the Rocknest soil, derived 
by Rietveld refinement on the CheMin XRD patterns 
2Th Degrees
5045403530252015105
C
ou
nt
s
9,000
8,000
7,000
6,000
5,000
4,000
3,000
2,000
1,000
0
-1,000
-2,000
Pigeonite 11.30 %
Ilmenite 0.72 %
Quartz 1.67 %
Anhydrite 1.37 %
Magnetite 1.83 %
Augite Px 16.58 %
Sanidine Na0.14 2.35 %
 
Figure 1. CheMin X-ray diffraction pattern, 1-D, for Scoop 
#5 of the Rocknest soil. Blue is pattern as measured, red is 
fitted pattern, gray is difference. The difference peak at 
~25.5° 2 is diffraction from the Al filter on the CCD light 
https://ntrs.nasa.gov/search.jsp?R=20130009989 2019-08-31T00:03:31+00:00Z
[b], are closely similar to those of Adirondack olivine 
basalt from Gusev (Table 1), and like those of the El 
Dorado sand except for proportion of the pyroxenes. 
The Rocknest mineral proportions are not (in general) 
similar to those of martian meteorites. As noted by 
others, fresh martian basaltic materials analyzed by the 
MER rovers are richer in plagioclase than the meteor-
ites (Table 2) except the Bounce Rock basalt. The 
crystalline component of the Rocknest soil is similarly 
rich in plagioclase.  
Adirondack Basalt. The Adirondack basalt, ana-
lyzed at the MER Spirit landing site, is conspicuously 
similar to the crystalline component of the Rocknest 
soil in mineralogy, mineral proportions, and mineral 
chemistry (Table 1). The similarity is so great that 
these two materials may be identical within uncertain-
ties. Perhaps the most obvious difference, quartz in the 
Rocknest crystalline component, may not be petrologi-
cally significant. Quartz and olivine of intermediate-
Mg# are not stable together but can be present in a 
crystalline basalt that cooled rapidly and underwent 
fractional crystallization [h]. In that case, quartz would 
be present in the rock but not appear in the normative 
mineralogy.  
Regional Setting. The source of the crystalline 
component of the Rocknest soil is not known. It is not 
related to any rock analyzed so far at Gale crater (e.g., 
Jake_Matijevic, Bathurst_Inlet, Rocknest_3). Surpris-
ingly, the Rocknest soil is not rich in crystalline sul-
fates, as might be expected from its proximity to the 
sulfate-rich rocks of the Gale Crater mound, Mt. 
Sharp. The crystalline component of the soil could, as 
it appears, be derived from a single basalt surprisingly 
like Adirondack (Table 1). This would require that 
basalts like Adirondack occur both at Gusev and Gale, 
even though the Adirondack-class basalts are signifi-
cantly fractionated, and are not primary mantle prod-
ucts [h].  
It is also possible that the crystalline component of 
the sand is a mixture of many different basalts, al-
though one would expect differential weathering, 
comminution, and sorting during extended eolian 
transport. In this case, the similarity of the Adirondack 
basalt to the crystalline component of the Rocknest 
soil would be coincidental.  
 
Supported by the MSL Mission (NASA), and by contri-
butions from the authors’ home institutions.  
References: [a] Blake D.F. et al. (2012) Space Sci. Rev. 
online. [a’] Blake D.F. et al. (2013) this volume. [b] Bish 
D.L. et al. (2013) this volume. [c] Morrison S.M. et al. 
(2013) this volume. [d] Morris R.V. et al. (2013) this vol-
ume. [e] Ming D.W. et al. (2008) JGR 113, E12S29. [f] Mor-
ris R.V. et al. (2008) JGR 13, E12S42. [g] Karner J. et al. 
(2004) Amer. Mineral. 89, 1101-1109. [h] Filiberto J. et al. 
(2008) MaPS 43, 1137-1146. [i] Schwenzer S.P. et al. (2012) 
EPSL 335-336, 9-17. [t] Duke M.B. (1968) 613-621 in: 
Shock metamorphism of natural materials. Mono Book 
Corp. [u] Warren P.H. & Kallemeyn G.W. (1997) Antarct. 
Met. Rsch. 10, 61-81. [v] Kring D.A. et al. (1996) Lunar 
Planet. Sci. 27, 705-706. [w] Filiberto J. et al. (2012) MaPS 
47, 1256-1273. [x] McSween H.Y.Jr. & Jarosewich E. 
(1983) GCA 47, 1501-1513. 
 
 
Table 1. Mineral Proportions of Rocknest Soil (CheMin XRD) and Normative Mineralogies of Basaltic Materials from  
Gusev Crater and of Martian Meteorites. Rocknest Data are Amorphous-Free Values.  
Location Gale  Gusev   Meteorites  
Sample Rocknest Soil  
Adiron-
dack Backstay Irvine El Dorado Shergotty
NWA 
6234 
EETA 
79001A 
QUE 
94210 
Quartz 2 0 0 0 0 0.2 0 0 3 
Plagioclase 43 39 49 32 41 23 19 19 32 
K-spar 2 1 6 6 2 1 0.5 0 0 
Low-Ca Pyx 11 15 14 21 20 46 30 47 15 
High-Ca Pyx 17 15 5 13 10 25 16 16 38 
Olivine 21 20 15 16 15 0 27 13 0 
Fe-Cr oxides 3 6 4 6 5 3 4 2 0 
Ilmenite 1 1 2 2 1 2 2 1 4 
Apatite - 1 3 2 2 2 2 1 6 
Anhydrite 1         
          
Mg# 58±3 57 62 55 62 51 63 63 40 
An 50±3 42 29 19 33 51 50 60 62 
Rocknest Soil by CheMin [b], average of scoop 5, proportions of crystalline phases normalized to 100%; values in italics 
uncertain, see text. CIPW norms (weight) for Gusev basaltic materials from MER APXS chemical analyses [e] ignoring S & 
Cl; Fe3+/Fetot for Backstay and Irvine taken as 0.17, the value for RATted Adirondak and El Dorado [f]. CIPW norms 
(weight) of Martian meteorites from bulk compositions [t-x]; Fe3+/Fetot as analyzed, and estimated at 0.1 for NWA 6234 and 
0 for QUE94201. ‘K-spar’ is sanidine for the Rocknest soil, and normative orthoclase for others. ‘Low-Ca Pyx’ is pigeonite 
for the soil, and normative hypersthene for others. ‘High-Ca Pyx’ is augite for the soil, and normative diopside for others. 
‘Fe-Cr oxide’ includes magnetite, hematite and chromite. All phosphorus in analyses calculated as normative apatite. 


Basaltic Soil of Gale Crater: Crystalline Component Compared to Martian Basalts and Meteorites

Basaltic Soil of Gale Crater: Crystalline Component Compared to Martian Basalts and Meteorites

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